Relier Pairs Talking About FunctionsVersion en ligne Matching par Logos Sprachinstitut 1 The shelf is bolted to the wall with screws. 2 The purpose of the wheel is to steer the truck. 3 The purpose of the backup file is to keep our data safe. 4 The vehicle is powered by the engine. 5 The airflow is regulated by the valve. 6 The bridge is supported by steel pylons. 7 The function of the switch is to turn the machine on and off. The backup file keeps our data safe. Screws bolt the shelf to the wall. The wheel steers the truck. The valve regulates the airflow. The switch turns the machine on and off. Steel pylons support the bridge. The engine powers the vehicle.